Recent aggravation of air pollution and soil pollution has rapidly acidified growth conditions of plants. Also, such pollution seriously inhibits the growth and activity of microbes that inhabit soils, resulting in a significant decrease of soil fertility.
In addition, overuse of agricultural chemicals causes serious medical and social problems. For example, in Korea, hundreds of farmers are directly poisoned causing significant health problems or even resulting in death by agricultural chemicals. What is worse, a multitude of consumers are also threatened by the agricultural products contaminated with chemicals. In fact, nowadays, the agricultural products, which are usually eaten, are frequently reported to be sold at markets while being contaminated with chemicals. Further, contamination of streams with agricultural products destructive to their ecosystems, causing pollution-related diseases.
Referring to a survey of the Korea Consumer Protection Board, methyl thiophene was detected at an amount of 0.2-7.7 ppm in some bean sprouts which were sold unpacked in Korea. This agricultural chemical is a precursor of cabendazim, a compound of carcinogenicity and teratogenicity. That is, a modified form of methyl thiophene may cause cancers or childbirth abnormalities. Thiophanate methyl is a main ingredient of Homai, an agricultural chemical which is typically used to wash various seeds, such as rice seeds, onion seeds, bean seeds, sesame seeds, before seeding. However, thiophanate methyl is legally prohibited from being used for the cultivation of bean sprouts as it is decomposed into cabendazim by the metabolism of bean sprouts themselves. Because Homai can prevent the putrefaction and discoloration of bean sprouts during their cultivation in addition to washing the seeds, it may be used before seeding and during cultivation.
Typical factors to shorten distribution periods of agricultural products include microbe-causing putrefaction, oxidization, and enzyme-causing quality degradation. Thus, to improve the preservation of agricultural products, antimicrobial agents and/or antioxidants are employed. As a result of such synthesis chemicals, including antimicrobial chemicals and growth-stimulating chemicals, it is not too much to say that almost all of the foods people usually eats are contaminated with agricultural chemicals.
Nutritionally comparing with meats, beans are rich in proteins and lipids. In particular, bean sprouts, which are germinated from beans, are a very popular food material and serve as a nutrition source in Korea. During the cultivation of bean sprouts, treatment with growth-stimulating agents reduces their average height by about 35% while making their hypocotyl parts thicker by about 40%. Such chemocultivation of bean sprouts, however, suffers from a serious problem in that chemicals remain in the food and thus, threaten the health of the consumers.
In order to solve such problems, various seed germination and plant growth stimulants of low toxicity have been developed. For instance, Korean Pat. Laid-Open Publication No. 95-702387 suggests laminarin as a stimulating agent for seed germination and plant growth. In Korean Pat. Laid-Open Publication No. 84-3383, there is disclosed a plant growth controlling agent which comprises at least one substituted naphthalene in addition to 1,4- and 1,6-dimethyl naphthalene, and an inert carrier or diluent. Another plant growth controlling agent can be referred to Korean Pat. Laid-Open Publication No. 88-12159 in which dialkylimidazolyl phosphate and dialkylimidazolyltetraraphosphoate are used as main ingredients. These compounds disclosed in the above-cited references, however, are synthetic compounds which cannot guarantee their safety to the human body. Korean Pat. Laid-Open Publication discloses a composition comprising elvan, phosphorite, glauconite and magnesite, asserting that it acts to improve soil fertility and stimulate plant growth. However, this composition is poor in such effects.